Method and apparatus for assembling flexible sheet material into frames

ABSTRACT

The present disclosure is directed to an automated method for assembling flexible sheet material into a grooved frame and an apparatus for performing the method, wherein a pair of generally transversely spaced carriage means carrying pressing rollers are selectively, cyclically, sequentially and intermittently moved relative to each other in a generally transverse direction so that the rollers are effective to roll the flexible material into spline grooves formed in window frames and the like, thereby eliminating the necessity for longitudinally moving and/or rotating said frame during the assembling operation.

Unite tees Wyrick [4 1 Dec. 3, 1974 [22] Filed:

[ METHOD AND APPARATUS FOR ASSEMBLING FLEXIBLE SHEET MATERIAL INTOFRAMES [76] Inventor: Auvis Malvin Wyrick, PO. Box 853,

Magnolia, Ark. 71753 May 9, 1973 [21] Appl. No.: 358,474

[52] US. Cl. 140/109, 29/200 B, 29/448, 29/462 [51] Int. Cl B2lf 33/00[58] Field of Search 140/108, 109; 29/417, 462, 29/448, 525, 33 F, 200R, 200 B Primary ExaminerC. W. Lanham Assistant Examiner-Victor A. DiPalma Attorney, Agent, or Firm-Cushman, Darby & Cushman [5 7] ABSTRACTThe present disclosure is directed to an automated method for assemblingflexible sheet material into a grooved frame and an apparatus forperforming the method, wherein a pair of generally transversely spacedcarriage means carrying pressing rollers are selectively, cyclically,sequentially and intermittently moved relative to each other in agenerally transverse direction so that the rollers are effective to rollthe flexible material into spline grooves formed in window frames andthe like, thereby eliminating the necessity for longitudinally movingand/or rotating said frame during the assembling operation.

14 Claims, 3 Drawing Figures H L l Ill 7 36 n :1 5;

I28 26 30 30 B0 32 6 25 /24 L Mtz 2a 92 72 941 A26 l2 78 //6 //8PATENTEL E55 3 I974 SIEEI 20F 3 METHOD AND APPARATUS FOR ASSELINGFLEXIBLE SHEET MATEAL INTO vali BACKGROUND OF THE INVENTION BRIEFDESCRIPTION OF THE PRIOR ART Heretofore, the conventional steps foreffectively assembling screen wire mesh into generally rectangularspline grooves on door or window frames were done manually. The manualmethod required the presence of several operators to accurately handroll the mesh into each spline groove. Not only does the manualoperation require several operators, but it additionally requirescumbersome steps, wherein the individual doing the rolling must eitherchange his position or reorientate the frame so that all the sides ofthe generally rectangular spline groove have the meshed rolled therein.Quite apparently, the manual method suffers from several distinctdisadvantages, among which is the fact that it requires the expenditureof many man hours and capital.

Another prior art method for screening frames is disclosed in the US.Pat. No. 2,695,445, to Johnson et al., wherein there is described amethod for rolling screen mesh into a frame as the mesh and framesequentially move along on two conveyors oriented at right angles toeach other. While this method continuously assembles screens, it does soin a manner which requires complicated equipment and greater floorspace, thereby resulting in an uneconomical and inefficient method.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to overcome the aforementioned disadvantages prevalent in theprior art. This object is accomplished by an automatic method and anapparatus for performing the method, wherein flexible sheet material,preferably screen mesh, is rolled into a generally rectangular grooveformed in a frame that is stationarily secured on a working table. Theapparatus of the invention comprises at least two pairs of pressingrollers, wherein each pair of rollers is carried by a first and secondmovable carriage means. The carriage means are mounted for selective,cyclical, sequential, intermittent and transverse movement relative toeach other. The method is accomplished by tensioning flexible sheetmaterial over the rectangular groove in the frame and thereafteractuating the first of the movable carriage means so that the pair ofpressing rollers thereon is effective on its working stroke to'engageand press the flexible sheet material into a first pair of opposedparallel grooves in the frame. After performing this step of theoperation, the first movable carriage reverses its initial direction ofmovement and returns to the starting position. During this return, therollers are lifted upwardly from the table so that they will not contactother structures. Also, the first carriage contacts a relay switch thatcauses the second carriage to perform its working stroke movement. Thismovement is generally transverse to the working and return strokes ofthe first carriage and by means of the pressing rollers is efi'ective toroll the flexible sheet materials into the second pair of opposedparallel grooves forming the sides of the generally rectangular groovedframe. After completion of this working stroke, the second movablecarriage is returned to its initial position. Thus, the screen mesh isexpeditiously rolled into the grooves by a cyclical, sequential andintermittent motion of the two movable carriages. This automatic methodand apparatus for accomplishing the same is a vast improvement over theaforementioned prior art techniques, in that a greater number of framescan be screened in a manner that uses less complicated machinery, fewerman-hours of labor, and less capital outlay.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I. is a generally planar view ofthe flexible sheet assembling apparatus made in accordance with theprinciples of this invention;

FIG. 2 is a front elevational view of the apparatus as shown in FIG. ll;and

FIG. 3 is a side elevational view of the apparatus illustrating otherfeatures of the apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Proceeding, therefore,to describe the invention in detail, reference should be made to FIG. 1of the drawings. As is seen in FIG. I, the screening apparatus 10 ismounted upon a frame 12. The frame includes two pairs of parallelgenerally elongated guide bars 14a, 14b, that are secured in atransverse fashion to the frame. Furthermore, the first pair 14a isvertically spaced from the second pair 14b for reasons that will laterbecome obvious.

Attached to each pair of guide bars 14a, Mb by means to be hereinafterdescribed, are a first and second movable carriage l6, and 18,respectively, that are mounted for cyclical, sequential, intermittentand transverse movement relative to one another.

The first and second movable carriages are generally identical instructure. Each carriage means includes at least two parallel journalhousings 20, 20 and sideplates 22, 22, movable in unison relative to theguide bars 14a, Mb. The journals permit the carriages to move relativeto the guide bars. Extending between and connected to each pair of sideplates is a transverse bar 24. Also extending between and rotatablyattached to each of the side plates 22 is an elongated roller bar 26.The roller bars carry a plurality of twin pressing rollers 28 that arepreferably arranged in pairs and are spaced at intervals relative toeach other. The roller bars are actuated to rotate by means, hereinafterdescribed, so that the pressing rollers can be lowered and raised duringboth the working and return strokes of the carriages, thereby onlycontacting the flexible sheet material M. (See FIG. 2). While thematerial to be later described is screen wire mesh, other flexible sheetmaterials can also be used, for instance, plastic. Each of the rollershas a circumferential pressing edge and a carriage 30.. The carriage isselectively movable relative to the roller barsso that the spacingbetween each of the carriages can be varied and in this way accommodatevarious dimensioned articles to be screened.

Extending laterally inwardly from each journal is a pair of flanges 32.Fastened to each flange is one end of a conventional chain belt 36.Although a chain belt is hereindescribed in the preferred embodiment, itis to be understood that other equivalent structures which function in alike manner can be used, for instance, a V-belt.

A first and second set of sprockets 36, 38 are operatively connected toeach chain connected to each journal. The sets of sprockets 36, 38 areconventionally mounted for rotation on brackets 40 that extend outwardlyfrom the frame 12. Arranged so as to be connected between respectiveones of the sets of sprockets is a drive shaft 42. The drive shaftrotates the sprockets, by means hereinafter described, thereby movingboth I carriages 16, 18.

Two variable speed motors 44,46 are suitably attached to the frame 12.Any conventional drive transmission can be used to impart rotation ofthe motors to the drive shafts 42.

As shown in this embodiment, the transmission is comprised of sprockets48 each of which are attached Each of the pressing rollers 28 attachedto the roller bars 26 can be regulated so as to vary the pressureexerted thereby on various types of flexible sheet material. In thismanner, a greater variety of flexible sheet material can be rolled intothe grooves. The device for effecting this change in pressure is moreclearly depicted in FIG. 2.

The device includes a vertically extending support bracket 56, a tensiontype coil spring 56, a chain link 60 and a sprocket 62 attached to therotatable bar 26. The vertical support bracket extends upwardly from theframe 12 and is supported thereby by a pair of inclined braces 64. Atthe top of the support bracket 56 is a flange 66 having a conventionalscrew-threaded means 66 extending through an aperture (not shown) whichis suitably attached to the coil spring 58. The opposite end of the coilspring is conventionally secured to the chain link 60. The chain link inturn is connected to the sprocket 62. By vertically adjusting thescrewthreaded means 68, the tension in the coil spring can be varied.This change in tension is efiective to vary the force the pressingrollers can impart by slightly rotating the roller bar 26 so that therollers move upwardly or downwardly relative to the screen mesh M.

As seen in FIG. 1, a bed 70 is defined by a plurality of transverselyextending bars 72 upon which a support surface or working table 76 issecurely mounted. Located at opposite ends of the table are a clampmechanism 76 and a roller tension mechanism 78.

The screen clamp mechanism is defined by two clamps 80 attached to aplate 82 extending along one end of the working table. The two clampsare pivotally movable between an engaged position and a disengagedposition. In the engaged position, the clamp is in a generallyhorizontal position and contacts the screen mesh M, while in thedisengaged position the clamps are in a generally inclined position. Oneend of the respective clamps has attached thereto a vertical rod 84 thatis effective to pivot the clamps about a pivot axis defined by a shaft(not shown) which extends through the clamps and mounting brackets 86associated with each of the clamps. Any conventional means (not shown)can be effective to impart movement to the clamps.

Located at the opposite end of the working table 74 is the tensionroller mechanism 78. This mechanism as shown more clearly in FIGS. 1 and2 is comprised of a drive roller 88 and a driven roller 90 having aclearance therebetween for the passage therethrough of the screen meshM. One of the transverse bars 72 has affixed thereto an electric motor92. The electric motor is connected to the drive roller 88 by aconventional chain and sprocket arrangement 94. When the electric motoris operated the drive roller cooperates with the driven roller so thatthe screen mesh M is drawn in a direction away from clamps 80.

The clamp mechanism 76 and the roller tension mechanism 78 are effectiveto operate simultaneously so that one end of the screen mesh M is heldby the clamps while the other end is pulled in a direction away from theclamps so as to apply the tension required.

As more clearly depicted in FIG. 2, the screen mesh is wound in a roll96 about a shaft 98. The shaft is rotatably secured by conventionalmeans to a mounting device 100 attached to the side of the frame 12.Located at the side of the frame 12 are a pair of variable speed controlswitches 102 each operative with one of the respective variable speedmotors 44, 46 for adjusting the speed of the latter.

A starter switch 104 is comprised of a longitudinally extending bar 106that is effective to operate the variable speed motor 44 when thestarter bar 106 is pulled away from a mounting bracket 108.

A press switch 110 attached to the frame 12 is operatively connected tothe clamp mechanism 76 and tension roller mechanism 78 so as tosimultaneously actuate the two mechanisms. Mounted for slidingadjustment on the frame 12 is a reversing switch 112 and a relay switch114. The reversing switch is selectively adjustable on the frame so asto preferably be positioned at a distance from the endmost extremity ofa conventionally grooved window or door frame 116 mounted on elements118 on the table (See FIG. 1). In this manner, the reversing switch ispositioned so that it will not be contacted by the first carriage 16until the pressing rollers 28 have rolled the screen mesh into the wholelongitudinal extent of the first pair of opposed grooves that extend inone of the transverse directions along the frame 1 16. The reversingswitch 1 12 is selectively operated to effect movement through theworking and return strokes of the first carriage. By being adjustablethe reversing switch can accommodate window or door frames of differentlengths. When the reversing switch is contacted it is also effective torelease the clamps 80 and cease the operation of the roller tensioningmechanism 78.

During the return stroke of the first carriage, the relay switch 114 iscontacted. The relay switch is operably connected to the variable speedmotor 46 so as to actuate the latter and initiate the working stroke ofthe second carriage 18.

As seen in FIG. 3, there is another reversing switch 120 and a cut-offswitch 122. The reversing switch is also capable of selective adjustmentrelative to the thereby accommodating frames 116 of various lengths.

The reversing switch 120 is also effective to cause the second carriageto initiate the return stroke so as to return it to the initialposition. During this return stoke the second carriage will contact thecut-off switch 122 that stops operation of the motor 46. Although theelectrical circuitry connecting the switches and the motors is notshown, it is believed such a circuit is obvious to one of ordinary skillin the art.

In order to insure that the pressing rollers 28 do not contact anystructure other than the screen mesh positioned over the grooves, aplurality of tension relief bars 124 are positioned in the path of thefirst and second carriages. The tension relief bars are placed onelongated support members 126 of the frame. When the rotatable rollerbar 26 carrying the pressing rollers 28 operatively contacts the tensionrelief bars, the roller bars pivot upwardly, thereby causing thepressing rollers to similarly move upwardly. Conversely, when the rollerbars no longer operatively contact the tension relief bars, the pressingrollers pivot downwardly. The mechanism used to effectuate this pivotingof the roller bars is a cam link 128 attached to the bar at one end andhaving a cam roller 138 attached at the opposite end thereof. The camrollers are effective to roll along and contact as well as follow thecontours of the tension bars 124 and support members 126. At the initialor starting positions of the carriages, the rollers contact the tensionbars causing the pressing roller to pivot upwardly out of contact withthe surrounding structure. The tension relief bars are correlated to theposition of the frame 116 so that the pressing rollers only pivotdownwardly to contact the screen mesh M located over the spline grooves.At least two tension bars are shown on each support member 122 so as toraise and lower the pressing rollers at both ends of the stroke.Appropriate means (not shown) can selectively adjust the position oftension relief bars and in this manner accommodate window or door framesof various sizes.

From the foregoing detailed description of the preferred embodiment itshould be understood that the apparatus operates in the followingmanner. The leading edgeof a screen mesh is inserted through theclearance between the roller 88, 90. The leading edge after being pulledthrough the rollers is passed over the window or door frame 116 until itis adjacent the end of the working table 74.

Thereafter, an operator actuates the press switch 108 to effect aclamping of the screen mesh and frame by the clamps 80. Simultaneously,the motor 92 is operated so as to rotate the drive roller 88 by thechain and sprocket arrangement as so as to cooperate with roller 90 andthereby apply a tension to the screen mesh.

After the clamping and the tensioning mechanisms have been effective toboth stationarily secure and apply the tension required, the operatorthen pulls outwardly on the starter bar 186 so as to effectuateoperation of the variable control motor 44. The variable control motorrotates the shaft 50 which effectuates move ment of the shaft $2 throughthe chain 54 and sprockets 48, 52. The shaft 42 in turn rotatessprockets 36 which cooperate with the chains 38 connected to thejournals 28 to move the first carriage 16. As the first carriage moves,the cam link 1128 moves therewith. Thusly, the cam roller 130 rides offthe tension relief bar 124 and this causes the pressing rollers 28 torotate downwardly and contact with the screen mesh M over the splinegrooves in the frame 116. The pressing rollers then roll the screen meshlVl into the spline grooves in such a manner as to secure a tightfrictional engagement therebetween.

The first carriage will move in the working stroke along a path definedby the guide bars 14a. The first carriage moves in this path until itcontacts the reversing switch 112. As noted the reversing switch can beadjusted relative to the frame 116 at a longitudinal distance away fromthe edge thereof, so as to permit the pressing rollers to effectivelyroll the screen mesh into the spline grooves along the longitudinalextent thereof. The cam rollers 1311 move along the support members 126and as they near the end of the working stroke contact another tensionrelief bar 124. This bar is so positioned that the cam rollers contactit shortly after the pressing rollers finish rolling the screen meshinto the longitudinal extent of the spline grooves and cause thepressing rollers to rotate upwardly, thereby not contacting otherstructures.

Also occurring at the working of the sorking stroke is a contact of thefirst carriage with the reversing switch 112. This actuates the switch 112 so as to operatively release the clamps and deactivate the electricmotor 92 so as to cease operation of the rollers 88, 90. In other words,the clamps are raised to their inclined position above the table byappropriate downward movement of the vertical rod 84. This raising ofthe clamps permits the pressing rollers of the second carriage to rollthe screen mesh into the remaining spline grooves on the frame 116. Thereversing switch 112 also activates the motor 44 so as to cause thefirst carriage to return to its original position.

During return stroke of the first carriage, the relay switch 114 iscontacted. The relay switch operates the variable speed motor 46operatively connected with the second carriage 18. As noted, the chains34 and sprockets 38 are effective to transmit the output of the variablespeed motor 46 to the second carriage and cause it to move in itsworking and return strokes.

The tension relief bars 124 cause the pressing rollers 28 of the rollerbar 26 to rotate downwardly. This insures the contact of the pressingrollers with the screen mesh above the spline grooves. in this mannerthe tension relief bars are effective to prevent the pressing rollers 28from contacting material other than the screen mesh located above thespline grooves. Another tension relief bar situated at the end of theworking stroke of the second carriage raises the rollers 28 away fromcontact with other structures.

The working stroke of the second carriage 18 continues until it contactsthe reversing switch 120. This reversing switch causes the variablespeed motor 46 to change the stroke of the second carriage. As thesecond carriage returns to itsinitial position, it contacts the cut-offswitch 122 which is efiective to stop operation of the apparatus 10.Before the cut-off switch is contacted by the second carriage, thetension relief bar 124 located at the beginning of the working stroke iseffective to rotate the pressing rollers upwardly. As noted, this upwardpivotal movement results from the contact of the links 128 and camroller 130 with the tension bar.

if it is desired to effectuate an adjustment of the pressure exerted bythe pressing rollers, an operator can, by merely turning the screwthreaded means 68 adjust the the screw threaded means is movedvertically upwardly or downwardly, the pressure rollers will pivotdownwardly or upwardly, thereby varying the pressure exerted by thepressing rollers.

Thus, there is described a method and an apparatus for performing amethod whereby a more efficient and effective manner of assemblingflexible sheet material to frames is accomplished. For instance, themethod and machine hereinabove described can if desired cycle in about16 seconds and is effective to roll or screen approximately 120 unitsper hour. This work output represents production of two skilled workersusing hand operated rolling means. Thusly, if two workers are operatingthe apparatus wherein one of the workers is placing vinyl spline afterthe mesh has been rolled into the spline grooves the work output ofthese two workers would be the full equivalent of four operatorsperforming the same method manually.

Although the invention is shown and described hereinabove in what isconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom wthin the scope of theinvention, which is not to 'gbe limited to the details disclosed but isto be accord'tithe full scope of the following claims so as to embri'ceany and all equivalent structures and/or steps.

What is claimed as novel afid unobvious and desired to be protected byLetters Pat t is set forth in the appended claims.

What is claimed is:

1. Apparatus for assembling flexible sheet material into a grooved framecomprising:

a support surface;

means to affix the frame to the surface and the sheet material over theframe and the. grooves thereof;

a first carriage means having two rollers thereon;

means to move the first carriage means across the frame to roll thesheet material into the grooves on two sides of the frame;

a second carriage means having two rollers thereon;

and

means to move the second carriage means across the frame to roll thesheet material into the grooves on the remaining two sides of the frame.

2. The apparatus as defined in claim 1, wherein the means of affixingthe frame to the surface and the sheet material over the frame andgrooves thereof is comprised of:

a clamping means selectively operated for contacting the frame and thesheet material being held on the surface; and

roller means selectively cooperating with the clamping means and thesheet material for applying a tension to the sheet material over theframe.

3. The apparatus as defined in claim 1, wherein the movement of each ofthe first and second carriage means is in a path defined between a firstposition and a second position, with each of the second positionsdetermined by the position of a separate reversing means, whereby thereversing means are effective to cause the first and second carriagemeans to return to the first po-.

sitions upon a contact therebetween.

4. The apparatus as defined in claim 3, further comprising:

a first actuation means that is activated by the first carriage meansreturning to the first position for actuating the means to move thesecond carriage means; and l g 5 a second actuation means that isactivated by the second carriage means returning to the first positionfor deactivating the means moving second carriage means.

5. The apparatus as defined in claim 3, wherein the reversing means arereversing switches.

6. The apparatus as defined in claim 4, wherein the first actuationmeans is a relay switch.

7. The apparatus as defined in claim 4, wherein the second actuationmeans is a cut-off switch.

8. The apparatus as defined in claim 4, further comprising:

means operatively associated with the first and second carriage meansthat are effective to selectively raise and lower the rollers thereonfor insuring that the rollers will roll the sheet material into thegrooves as long as the rollers are vertically adjacent the grooves.

9. The apparatus as defined in claim 8, wherein the means selectivelyraising and lowering the rollers comprises:

follower means operatively connected to the rollers on both the firstand second carriage means; and relief means adjustably positionedrelative to both paths of the first and second carriage means forcontact with the follower means so that when the follower means contactsthe relief means the rollers are raised from the sheet material and theframe.

10. The apparatus defined in claim 9, wherein the follower means is acam follower and the relief means are at least one generally elongatedbar upon which the cam follower selectively rides.

11. The apparatus as defined in claim 1, wherein each of the rollers ofboth the first and second carriage means are selectively adjustablerelative to the first and second carriage means for accommodating framesof various sizes.

12. The apparatus as defined in claim 1 further comprising:

means for selectively varying the magnitude of pressure the rollersexert on the sheet material, thereby providing a range of pressure thatpermits different types of sheet material to be rolled into the grooves.

13. A method of assembling at a single work station flexible sheetmaterial into a four-sided groovedframe having a groove in each sidethereof forming first and second pairs of grooves in opposed sidesthereof, said method comprising the steps of a) securing said frame to astationary support with the sheet material overlying said frame and saidgrooves therein, said sheet material having the upper surface thereoffacing away from said frame,

b) applying two rollers on a first movable carriage to said uppersurface of said sheet material to roll said material into said firstpair of grooves in opposed frame sides as said carriage moves, and

c) applying two rollers on a second movable carriage to said uppersurface of said sheet material to roll said material into said secondpair of grooves in opposed frame sides as said second carriage moves.

14. A method as recited in claim 13 comprising the further step ofapplying a spline along each of said grooves to secure said sheetmaterial therein.

1. Apparatus for assembling flexible sheet material into a grooved framecomprising: a support surface; means to affix the frame to the surfaceand the sheet material over the frame and the grooves thereof; a firstcarriage means having two rollers thereon; means to move the firstcarriage means across the frame to roll the sheet material into thegrooves on two sides of the frame; a second carriage means having tworollers thereon; and means to move the second carriage means across theframe to roll the sheet material into the grooves on the remaining twosideS of the frame.
 2. The apparatus as defined in claim 1, wherein themeans of affixing the frame to the surface and the sheet material overthe frame and grooves thereof is comprised of: a clamping meansselectively operated for contacting the frame and the sheet materialbeing held on the surface; and roller means selectively cooperating withthe clamping means and the sheet material for applying a tension to thesheet material over the frame.
 3. The apparatus as defined in claim 1,wherein the movement of each of the first and second carriage means isin a path defined between a first position and a second position, witheach of the second positions determined by the position of a separatereversing means, whereby the reversing means are effective to cause thefirst and second carriage means to return to the first positions upon acontact therebetween.
 4. The apparatus as defined in claim 3, furthercomprising: a first actuation means that is activated by the firstcarriage means returning to the first position for actuating the meansto move the second carriage means; and a second actuation means that isactivated by the second carriage means returning to the first positionfor deactivating the means moving second carriage means.
 5. Theapparatus as defined in claim 3, wherein the reversing means arereversing switches.
 6. The apparatus as defined in claim 4, wherein thefirst actuation means is a relay switch.
 7. The apparatus as defined inclaim 4, wherein the second actuation means is a cut-off switch.
 8. Theapparatus as defined in claim 4, further comprising: means operativelyassociated with the first and second carriage means that are effectiveto selectively raise and lower the rollers thereon for insuring that therollers will roll the sheet material into the grooves as long as therollers are vertically adjacent the grooves.
 9. The apparatus as definedin claim 8, wherein the means selectively raising and lowering therollers comprises: follower means operatively connected to the rollerson both the first and second carriage means; and relief means adjustablypositioned relative to both paths of the first and second carriage meansfor contact with the follower means so that when the follower meanscontacts the relief means the rollers are raised from the sheet materialand the frame.
 10. The apparatus defined in claim 9, wherein thefollower means is a cam follower and the relief means are at least onegenerally elongated bar upon which the cam follower selectively rides.11. The apparatus as defined in claim 1, wherein each of the rollers ofboth the first and second carriage means are selectively adjustablerelative to the first and second carriage means for accommodating framesof various sizes.
 12. The apparatus as defined in claim 1 furthercomprising: means for selectively varying the magnitude of pressure therollers exert on the sheet material, thereby providing a range ofpressure that permits different types of sheet material to be rolledinto the grooves.
 13. A method of assembling at a single work stationflexible sheet material into a four-sided grooved frame having a groovein each side thereof forming first and second pairs of grooves inopposed sides thereof, said method comprising the steps of a) securingsaid frame to a stationary support with the sheet material overlyingsaid frame and said grooves therein, said sheet material having theupper surface thereof facing away from said frame, b) applying tworollers on a first movable carriage to said upper surface of said sheetmaterial to roll said material into said first pair of grooves inopposed frame sides as said carriage moves, and c) applying two rollerson a second movable carriage to said upper surface of said sheetmaterial to roll said material into said second pair of grooves inopposed frame sides as said second carriage moves.
 14. A method asrecited in claim 13 comprising the further sTep of applying a splinealong each of said grooves to secure said sheet material therein.